1. Field of the Invention
The invention relates to a connection apparatus, and more particularly to a connection apparatus with high voltage impulse protection.
2. Description of the Related Art
Whenever electronic circuitry is coupled to an external cable run there is a risk of damage to the circuit, due to the transmission of transient overvoltages by the cable run. Transient overvoltages may be due to any one of several factors. For example, lightning, electrostatic discharge, or malfunctioning equipment at a remote end of the cable may be responsible. Several techniques exist for isolating circuitry from potentially damaging surges.
FIG. 1 is a schematic diagram of a conventional network connector. As shown, the network connector 100 provides high voltage impulse protection (also referred to as lightening or surge protection) between signal lines by transient voltage suppressor (TVS) diodes 10A˜10D and provides high voltage impulse protection between signal lines and a ground terminal by coupling resistors R1˜R4 and a capacitor CH to the pins TX+, TX−, RX+ and RX−.
The described method, however, has the following disadvantages. Energy caused the high voltage impulse may discharge to other components as the resistors have a large volume. To sustain the discharged energy, however, the volume of the resistors must be sufficiently large. Further, in order provided optimum isolation for a component, isolation glue must be coated on the printed circuit board, reducing yield and increasing time-to-market.
The currents through the each resistor may also be different due to resistance error in the resistors, such that the resistor with a relative smaller resistance may bear a larger current and thus be damaged. Total cost increases with the total number of resistors used. The resistors may age due to lightening. Additionally, there is no lightening protection for the secondary coils (TL3 and TL4), and thus, interference with the core of the system by lightening is not preventable. Typical integrated circuits are not capable of sustaining high voltage and although the primary coils (TL1 and TL2) isolate most discharged energy, a voltage of several tens of volts is still induced in the secondary coils and the motherboard may be damaged accordingly.